Gas blast circuit breaker



April 21, 1942. H. THOMMEN l 2,280,321

GAS BLAST -CIRCUIT BREAKER l Filed Feb. 8, 1940 iatented Apr. 2l, 1942GAS BLAST CIRCUIT BREAKER Hans Thommen, Baden, Switzerland, assigner toAktiengesellschaft Brown, Boverl & Cie., Baden,

Switzerland Application February 8, 1940, Serial No. 317,949 In GermanyNovember 17, 1938 (Cl. 20o-148) 8 Claims.

In order to check and diminish the frequency of the interruptions causedin networks by arc short circuits the conductors are quickly interruptedand switched in again by means of circuit breakers. The reclosingprocess should be performed so quickly that the power stations connectedto the network conductors do not fall out of synchronism. For thisreason the conductors should remain without voltage for only a fractionof a second. More recently this reclosing process has preferably beenundertaken by means of switching devices having arcing contacts forinterrupting current iiow and asecond set of contacts for the voltageisolation, a gas blast circuit breaker being used for interrupting thepower, this ensuring a sumciently short operating time. Such ,circuitbreaker arrangements can operate advantageously in such a manner thatfor a normal interruption both sets of contacts are opened in dependenceon each other and one after the other, whilst when a disturbance occursthe arclng contacts are reclosed at least once during which time thevoltage disconnecting contacts remain closed, but if the disturbanceprevails the conductor is automatically switched out due to both sets ofcontacts being opened. In all known circuit breaker arrangements of thiskind separate contact places are provided for interrupting the power anddisconnecting or isolating the voltage.

The present invention deals with a gas blast circuit breaker having asingle set of relatively y movable contacts that serve as an arcing gapsubjected to an air blast for interrupting the tion and the isolation ofthe volt-age is main- Several constructional examples are illustrateddiagrammatically in the accompanying drawing, Figures 1 to 3 showing asectional view of the pressure chamber, all parts which are notessential for an understanding of the invention having been omitted fromthe drawing. Figs. 4a, 4b and 4c are curves illustrating therelationship between the contact separation and time for three differentcharacteristic interruption conditions.

In Figs. 1-3, a represents a pressure chamber which for instance is madeof insulating material and contains the contacts b, c. Gas underpressure is supplied to the pressure chamber a through a main controlvalve from a pressure gas reservoir A and when switching out, this gasflows through the Contact gap formed by the contacts b, c to theatmosphere, after having first spread over and de-ionised the openingarc and if desired, also passing through a silencer or, cooler. On theoutflow side of the pressure chamber a is located a stop valve d thatresponds'to a gas blast through the contact gap to interrupt the blast.

In the constructional example shown in Fig. 1 the contact b is a nozzlecontact on the exhaust side of the pressure chamber a and thecountercontact c is a pin contact; both contacts are arranged to move inopposite directionsI in the pressure chamber. The nozzle contact b iscarried by a piston i in a cylinder having ports m, m at its' oppositeends for the admission of pressure gas from chamber a and from a conduitlc, respectively. A spring e moves the piston i downwardly to engage thecontacts b, c when the opposite sides of the piston i are subjected tothe same gas pressure, and the piston moves upwardly to separate thecontacts when pressure gas is admitted to the cylinder through port mbut not through the upper port m. The countercontact c is for instanceopened and closed by an electro-pneumatic control which is separate fromthe main control valve. In the example shown in Fig. 1 the power isinterrupted due to the nozzle contact b moving relative to thestationary pin contact c, whilst for isolating the voltage the pincontact is moved a further distance from the elevated nozzle contact.The lengths of travel of contacts b, c therefore vary according to thevarious kinds of switching operation performed. The stroke of the nozzlecontact b is smaller than that of the pin contact c because the formerrequires only to be moved such a distance that a gap is obtained whichis suitable for extinguishing the arc by means of the gas blast, Whilstthe pin contact c must be moved so arthat the required voltage isolationis achieved.

For a normal disconnection which can either be undertaken by hand or byremote control, the nozzle contact b is brought into the open positionand the opening arc is extinguished by the gas blast, the nozzle contactreturns to the closed position, and thereupon the voltage is isolated bymoving the pin contact c into its open posiopens into the cylinder ofpiston j' valve d is closed by the action of the outilowing pressure gaswhich passes through the valve bore to the rear side of the piston f andacts on this latter against the spring g. The conduit lc opens into thecylinder below the piston f to admit pressure gas when the valve d is tobe held in open position. After the voltage has been isolated the mainvalve can be closed.

The opening and the closing of the switch system may be controlled bythe usual relay circuits and electrically operated valves but, forsimplicity of illustration, are shown diagrammatically in Fig. l asmanually operable valves. The main valve V for initiating the opening ofthe switch system is located in the pipe or conduit n that connects thepressure storage tank A to the interior of the arcing chamber a. Theflow of pressure gas through conduit Ic is controlled by a valve v; andthe now of pressure gas to the cylinder B, for displacing the piston Cto lower the pin contact c for voltage isolation, is controlled by thevalve v in the conduit ic'.

When a fault occurs, a protective relay responds automatically to openthe main valve, corresponding to valve V of the diagrammaticallyillustrated control system of Fig. l, thereby to admit pressure gas tothe chamber a and to the lower face of the piston i through the port m,to initiate the opening movement of the nozzle contact b forinterrupting the power, so that the arc can be extinguished. Pressuregas is not admitted to the conduit k at this step in the circuit openingoperation. The separation of contacts b, c establishes anarc-extinguishing blast across the contact gap, and pressure gas passesto the upper face of the piston f through the hollow piston rod andthereby moves the piston f downwardly to interrupt the blast by closingthe outlet for the pressure gas. The valve d may be opened and thearcing contacts b, c again closed, the main control valve V being stillopen, by admitting gas under pressure through the pipe k to the upperside of the piston i of the nozzle contact b and also below the piston fof the valve d. Thereupon thernozzle contact b returns to its closedposition, the valve d opens and the contact place b, c is subjected to asecond gas blast upon the subsequent closing of valve v in pipe k. Whenreclosing, care must be taken that the valve d opens only after thecontacts b, c are closed. that is to say the pressure in the pressurechamber must be maintained during the reclosing operation. The reclosingoperation can if necessary be repeated by means of a suitablearrangement ofthe protective relays and the electro-pneumatic control,before the final disconnection is effected by moving the pin contact crelative to the stationary contact d.

In the constructional example illustrated in Fig. 2 lar contact throughwhich the pressure gas lcan ow to the atmosphere. This constructionnecessitates the provision of an additional stop valve d1, similar tovalve d, and carried by the hollow rod of a piston f' that is normallyheld in retracted position by a spring g'.4 The pipe k at the side thecontrol elementsl the pin contact c is constructed as a tubulla -contactin opposite directions.

adjacent the valve d'. The method of operation ot this arrangementcorresponds to that shown in Fig. 1.

Fig. 3 shows an arrangement in which a xed nozzle contact b1 is arrangedin the pressure chamber, the movable pin contact c beingelectropneumatically controlled in such a manner that it makes therequired movements for interrupting the power` and isolating the voltageone after the other. A stop valve d, such as described with reference toFig. 1, is provided above the fixed nozzle contact b1 to seal oi thepressure chamber a after the gas blast has extinguished 'the arc drawnbetween contacts brand c by the initial movement of the pin contact c.In a normal circuit opening operation, as indicated by the curve of Fig.4a, the pin contact c is initially moved a short distance into afavorable arc-extinguishing position and, after the extinction of thearc, is moved into the end position corresponding to voltage isolation.When the relay system effects a reclosure of the contacts b1, c beforethe voltage-isolation displacement of the pin contact c, the reclosingoperation is effected in accordance with the characteristic curve ofFig. 4b. If the fault is still on the Aline after this reclosure of thecontacts, the pinl contact c is again displaced a short distance for arcextinction, and is thus displaced further for voltage isolation, asshown by the curve of Fig. 4c.

The pin contact can in this case be constructed as a tubular contact, asshown in Fig. 2, so that the pressure gas can escape from the place ofAfter the ilrst partial travel stroke for interrupting the power hasbeen accomplished, the movable contact can be temporarily stopped by anyknown means. It is also possible for instance to compensate the movementof the contact by means of pressure gas so that the pin contact has anoscillating movement during the rst contact stroke.

Although several embodiments of the present invention have beenillustrated and described,.it

will be apparent to those skilled in the art that various changes andmodications may be made therein without departing from the spirit of theinvention or the scope of the appended claims.

It is claimed and desired to secure by Letters Patent:

l. In a gas blast circuit breaker, a pressure chamber, a nozzle contactextending through a wall of said chamber, a piston slidable in acylinder and carrying said nozzle contact, ports at the opposite ends ofsaid cylinder and opening into said pressure chamber and and a conduitrespectively, spring means urging said nozzle contact into circuitclosing position, a cooperating contact within said chamber for closingthe bore of said nozzle contact when said contacts are engaged, andvalve means at the exterior of said chamber and responsive to the flowof pressure gas through said nozzle contact to terminate the escape ofpressure gas through said nozzle contact upon a separation of saidcontacts.

2. In a gas blast circuit breaker, a pressure chamber, anozzle contactextending through a wall of said chamber, a piston carrying said nozzlecontact and slidable in a cylinder open to said chamber, a cooperatingcontact within said chamber, spring means in said cylinder urging saidnozzle contact into engagement with said cooperating contact; a valve atthe exterior of said chamber for closing the bore through said nozzlecontact, a piston and hollow piston rod carrying said valve, springmeans urging said valve towards open position, said hollow piston steinbeing alined with said nozzle contact to pass pressure gas to the rearof the associated piston to close said valve, and means for admittingpressure gas to said pistons to move the first piston intocontact-closing position and to move the 'second piston intovalve-opening position.

3. In a gas blast circuit breaker, a pressure chamber, a nozzle kcontactin said chamber and having a bore opening to the exterior thereof, acooperating contact in" said chamber, means for moving one of saidcontacts away from the other to separate said contacts for theinterruption of current ow, means for supplying pressure gas to saidchamber to establish an arc-extinguishing blast through the gap betweenthe separated contacts, means responsive to the blast through the boreof said nozzle contact to close said bore, and means for moving saidcooperating contact away from said nozzle contact for voltage isolation.

4. In a gas blast circuit breaker, a pressure chamber, a nozzle contactin said chamber and having a bore opening to the exterior thereof, a

cooperating contact in said chamber, means supporting said nozzlecontact for movement away from said cooperating contact for theinterruption of current ilow, means for supplying pressure gas to saidchamber to establish an arcextinguishing blast through the gap betweenthe separated contacts, means responsive to the blast through the boreof said nozzle contact to close said bore, and means for moving saidcooperating contact away from said nozzle contact for voltage isolation.

5. An electric circuit breaker comprising an arcing chamber having anoutlet, a pair of co- I\perating contacts arranged in said chamber,

means for separating said contacts, means for producing a uid blastacross said contacts for extinguishing an arc drawn therebetween uponseparation thereof, valve means for controlling the escape of pressureiluidlfrom said outlet upon a separation of said contacts, a iluidpressure motor operable in one direction by pressure iluid escaping fromsaid outlet to move said valve means into closed position to terminatethe escape of pressure fluid from said outlet, and means for admittingpressure iluid to said motor to operate the same in the oppositedirection to open said valve means.

6. An electric circuit breaker as claimed in claim 5, wherein said meansfor separating said contacts comprises means for initially separatingsaid contacts to draw an arc between the same, and means for effecting afurther separation of said contacts for voltage isolation.

7. An electric circuit breaker comprising an arcing chamber, a pair ofcooperating contacts within said chamber, each contact being hollow andhaving a bore opening to the exterior of the arcing chamber, means forseparating said contacts, means for admitting a pressure gas to saidarcing chamber to produce a blast across said contacts `forextinguishing an arc drawn therebetween upon separation thereof, thepressure gas escaping from said arcing chamber through the bores of saidcontacts, and means responsive to the escape of pressure gas throughsaid bores for closing the same.

8. An electric circuit breaker as claimed in claim 7, wherein said meansfor separating said contacts includes means operable individually tomove the respective contacts away from each other.

HANS THOMMEN.

